As the cost of renting rises and home values keep dropping, it gets easier and easier to figure out whether it’s smarter to buy or rent. A new study indicates that in 98 out of 100 U.S. housing markets, buying is the more affordable option.

According to data from the real estate site Trulia, the only metropolitan areas where it still makes more financial sense to rent rather than buy are San Francisco and Honolulu. Last summer, by comparison, buying was deemed more affordable than renting in three-quarters of the top 100 markets.

The areas where buying is much, much cheaper than renting tend to be older, down-on-their luck cities such as Detroit and Toledo and Cleveland, Ohio, according to CNN Money. The Detroit Free Press rounded up several former renters who are now paying much less each month on mortgages than they used to fork over to landlords. One retiree in the greater Detroit area, for instance, swapped his 2BR, 900-square-foot, $1,100-a-month apartment for a 4BR, 2,500-square-foot home with a $950 monthly mortgage payment.

There’s a reason why buying can be dramatically less expensive in these cities, though:

“Buying is much cheaper than renting in slow-growing places with high vacancy rates and land to spare like Detroit and Cleveland, where prices are unlikely to improve much in the future,” said Trulia’s chief economist Jed Kolko.

The rule of thumb is that if buying is 15 or more times more expensive than renting, then it’s smarter to rent. Overall in Detroit, it’s just 3.7 times more expensive to buy than rent—and in certain situations like the one mentioned above, it’s flat-out cheaper just to buy.

In San Francisco, by contrast, it’s 17 times pricier to buy than rent, so the advice for renters is to keep on renting. It may be surprising that Manhattan isn’t on the rent side of this equation. It should be, actually. Trulia estimates that the buy : rent price ratio in Manhattan is 20, meaning that it’s better financially to rent. But Trulia’s study covers 100 metro areas, and the New York City area includes Manhattan, as well as the outer boroughs and parts of the suburbs where buying is only 12 times pricier than renting.

Despite the fact that the rent-buy debate is overwhelmingly leaning toward the buy argument, qualifying for a mortgage isn’t as easy as it was in the past, and many would-be buyers remain understandably freaked out by the real estate crash of the past half-decade. What with the still-shaky state of employment, many also prefer to keep renting because they don’t want to tied to a mortgage, or to living in any particular city. In uncertain times, it seems wise to keep one’s options open.

So, instead of a sharp rise in people snatching up affordable single-family homes, what are we seeing? According to recent construction reports, there’s a steep increase in the number of multi-family housing being built—housing that’ll likely wind up occupied by renters.

Brad Tuttle is a reporter at TIME. Find him on Twitter at @bradrtuttle. You can also continue the discussion on TIME’s Facebook page and on Twitter at @TIME.